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295 citation(s) found for "Dyck, JR".

Neuropathy symptom and change: Inotersen treatment of hereditary transthyretin amyloidosis
Dyck, P. James B. , Coelho, Teresa , Brannagan, Thomas H., Khella, Sami, Polydefkis, Michael , Kincaid, John C., Wiesman, Janice F. , Litchy, William J. , Mauermann, Michelle L. , Ackermann, Elizabeth J., Baker, Brenda F. , Jung, Shiangtung W., Guthrie, Spencer , Pollock, Michael, Brannagan, T H , Mauermann, Michelle L , Baker, Brenda F , Waddington‐Cruz, Márcia , Karam, Chafic , Berk, John L.

Muscle & Nerve | July 12, 2020 | Volume: 62 | Issue: 4 | Pages: 509-515

10.1002/mus.27023 | PMID 32654156 Get It

AbstractIntroductionHereditary transthyretin‐mediated amyloidosis (hATTR) manifests as multisystem dysfunction, including progressive polyneuropathy. Inotersen, an antisense oligonucleotide, improved the course of neuropathic impairment in patients with hATTR in the pivotal NEURO‐TTR study (NCT01737398). To determine inotersen's impact on symptoms and patients’ neuropathy experience, we performed a post hoc analysis of the Neuropathy Symptoms and Change (NSC) score.MethodsStage 1 or 2 hATTR patients were randomized to receive weekly subcutaneous inotersen or placebo for 65 weeks. NSC score was assessed at baseline and 35 and 66 weeks.ResultsAt 66 weeks, inotersen‐treated patients had symptom stabilization as compared with worsening in patients receiving placebo, based on total NSC score. There were also improvements in the subdomains of muscle weakness, sensory, pain, and autonomic symptoms, and for various individual items.DiscussionInotersen treatment stabilized neuropathy symptoms, including autonomic symptoms, in patients with hATTR according to NSC score. Thus, the NSC may be an effective measure to assess neuropathy progression and patients’ neuropathy experience in clinical practice.
Determinants of Bone Material Strength and Cortical Porosity in Patients with Type 2 Diabetes Mellitus
Samakkarnthai, Parinya , Atkinson, Elizabeth J. , Achenbach, Sara J., Wennberg, Paul W. , Dyck, P. James B. , Tweed, Amanda, Volkman, Tammie L., Amin, Shreyasee , Sfeir, Jad G, Tweed, Amanda J, Farr, Joshua N. , Sfeir, Jad , Vella, Adrian , Drake, Matthew T. , Khosla, Sundeep

The Journal of Clinical Endocrinology & Metabolism | June 17, 2020 | Volume: 105 | Issue: 10 | Pages: e3718-e3729

10.1210/clinem/dgaa388 | PMID 32556277 Get It

Abstract Context Reduced bone material strength index (BMSi) and increased cortical porosity (CtPo) have emerged as potentially contributing to fracture risk in type 2 diabetes mellitus (T2DM) patients. Objective To determine whether BMSi or CtPo are related to other diabetic complications. Design Cross-sectional observational study. Setting Subjects recruited from a random sample of southeast Minnesota residents. Participants A total of 171 T2DM patients (mean age, 68.8 years) and 108 age-matched nondiabetic controls (mean age, 67.3 years). Main Measures Bone material strength index was measured using microindentation, skin advanced glycation end-products (AGEs) measured using autofluorescence, high-resolution peripheral quantitative computed tomography at the distal radius and tibia, assessment of diabetic microvascular complications including urine microalbuminuria, retinopathy, neuropathy, and vascular disease (ankle brachial index and transcutaneous oxygen tension [TcPO2]). All analyses were adjusted for age, sex, and body mass index. Results Skin AGEs were negatively correlated with the BMSi in both T2DM (r = -0.30, P < 0.001) and control (r = -0.23, P = 0.020) subjects. In relating diabetic complications to CtPo, we found that T2DM patients with clinically significant peripheral vascular disease (TcPO2 ≤ 40 mm Hg) had higher (+21.0%, P = 0.031) CtPo at the distal tibia as compared to controls; in these subjects, CtPo was negatively correlated with TcPO2 at both the distal tibia (r = -0.39, P = 0.041) and radius (r = -0.41, P = 0.029). Conclusions Our findings demonstrate that bone material properties are related to AGE accumulation regardless of diabetes status, while CtPo in T2DM patients is linked to TcPO2, a measure of microvascular blood flow.
SUN-381 Cortical Porosity Is Associated with Peripheral Small Vessel Disease in Adult Patients with Type 2 Diabetes
Wennberg, Paul W. , Dyck, Peter James , Achenbach, Sara J., Atkinson, Elizabeth J. , Tweed, Amanda, Volkman, Tammie L., Samakkarnthai, Parinya , Sfeir, Jad , Drake, Matthew T. , Farr, Joshua N. , Khosla, Sundeep

Journal of the Endocrine Society | May 8, 2020 | Volume: 4 | Issue: Supplement_1 | Pages: No page available

10.1210/jendso/bvaa046.1148 Get It

Abstract Patients with Type 2 Diabetes (T2D) are at higher fracture risk despite having relatively normal or even increased BMD by DXA. Increased cortical porosity has emerged as a potential factor contributing to fragility fractures in T2D. However, there is conflicting evidence whether T2D patients have increased cortical porosity. We hypothesized that microvascular complications have an important role in cortical porosity. Thus, we performed high-resolution peripheral quantitative computed tomography imaging at the distal radius and tibia to evaluate bone microarchitecture in men with T2DM age ≥ 50 yrs or postmenopausal women with T2DM and nondiabetic controls. Comprehensive diabetic complications were assessed in all patients including urine microalbuminuria, retinopathy, neuropathy (touch, temperature, and vibration sensation), ankle brachial index (ABI) and transcutaneous oxygen tension (TcPO2). Percent differences between groups were obtained from linear regression models adjusting for age, BMI, and sex. Relationships between variables were assessed using adjusted Spearman correlations. A total of 164 T2D patients (mean age 68.9 ±7.8 yrs.; 56.7% men; HbA1C=7.7 ±0.9%; mean diabetes duration 15.2 yrs.) and 107 nondiabetic controls (mean age 67.3±8.8 yrs.; 42.1% men; HbA1C =5.4 ±0.3%) were recruited to the study. Overall, there was a trend for increased cortical porosity at the distal tibia in the T2D group (+12.2%; p=0.063) compared with nondiabetic controls. Of note, TcPO2 was negatively correlated with cortical porosity at the distal radius (r= -0.17; p= 0.039) and distal tibia (r= -0.15; p= 0.073). In particular, the Low TcPO2 (≤40 mmHg) group (n=29) had greater cortical porosity at the distal tibia (+19.6 %; p=0.037) compared with the High TcPO2 (>40 mmHg) group (n=133). In addition, the low TcPO2 group had a significant increase in cortical porosity in the distal tibia (+24.8% p=0.020) compared with nondiabetic controls. In conclusion, this is the first evidence in humans indicating that TcPO2, a measure of microvascular blood flow, is linked to cortical porosity in the distal radius and tibia in T2D patients. Our findings may explain the conflicting findings regarding cortical porosity in T2D because only T2D patients with impaired microvascular blood flow have increased cortical porosity. Collectively, our data indicate that cortical porosity is a microvascular complication of longstanding T2D.
Early data on long‐term efficacy and safety of inotersen in patients with hereditary transthyretin amyloidosis: a 2‐year update from the open‐label extension of the NEURO‐TTR trial
Brannagan, Thomas H., Wang, A. K., Coelho, Teresa , Polydefkis, Michael , Dyck, P. James B. , Barroso, Fábio , Merlini, Giampaolo , Hughes, Stephen G. , Kwoh, Jesse, Jung, Shiangtung W., Guthrie, Spencer , Pollock, M. , Benson, M. D., investigators, for the NEURO‐TTR open‐label extension, Pinto, Marcus Vinícius , Campistol, Josep M. , Gámez, Josep , Brannagan, T H , Merlini, Giampaolo , Pinto, Marcus V , Waddington‐Cruz, Márcia , Planté‐Bordeneuve, Violaine , Berk, John L. , Conceição, Isabel , Hughes, S. G., Gertz, Morie A. , investigators, for the NEURO‐TTR open‐label extension

European Journal of Neurology | April 28, 2020 | Volume: 27 | Issue: 8 | Pages: 1374-1381

10.1111/ene.14285 | PMID 32343462 Get It

Background and purposeHereditary transthyretin (hATTR) amyloidosis causes progressive polyneuropathy resulting from transthyretin (TTR) amyloid deposition throughout the body, including the peripheral nerves. The efficacy and safety of inotersen, an antisense oligonucleotide inhibitor of TTR protein production, were demonstrated in the pivotal NEURO‐TTR study in patients with hATTR polyneuropathy. Here, the long‐term efficacy and safety of inotersen are assessed in an ongoing open‐label extension (OLE) study.MethodsPatients who completed NEURO‐TTR were eligible to enroll in the OLE (NCT02175004). Efficacy assessments included the modified Neuropathy Impairment Score plus seven neurophysiological tests composite score (mNIS + 7), the Norfolk Quality of Life – Diabetic Neuropathy (Norfolk QOL‐DN) questionnaire total score and the Short‐Form 36 Health Survey (SF‐36) Physical Component Summary (PCS) score. Safety and tolerability were also assessed.ResultsOverall, 97% (135/139) of patients who completed NEURO‐TTR enrolled in the OLE. Patients who received inotersen for 39 cumulative months in NEURO‐TTR and the OLE continued to show benefit; patients who switched from placebo to inotersen in the OLE demonstrated improvement or stabilization of neurological disease progression by mNIS + 7, Norfolk QOL‐DN and SF‐36 PCS. No new safety concerns were identified. There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of inotersen exposure.ConclusionInotersen slowed disease progression and reduced deterioration of quality of life in patients with hATTR polyneuropathy. Early treatment with inotersen resulted in greater long‐term disease stabilization than delayed initiation. Routine platelet and renal safety monitoring were effective; no new safety signals were observed.
Defining the pathophysiology of the paclitaxel-acute pain syndrome
Wolf, Sherry L., Loprinzi, Charles L. , Maddocks‐Christianson, Kami, Rao, R. D., Dyck, Peter, Mantyh, Patrick W. , Dyck, P. J., Dyck, P. B.

Journal of Clinical Oncology | March 6, 2020 | Volume: 25 | Issue: 18_suppl | Pages: 19613-19613

10.1200/jco.2007.25.18_suppl.19613 Get It

19613 Background: Paclitaxel therapy often results in a unique sub-acute pain syndrome, whose pathophysiology is unknown. While this syndrome is often termed as a ‘myalgia’ or ‘arthralgia’, it has not been demonstrated to be associated with any structural injury of muscles or joints. Identifying the pathophysiology mechanisms that result in the paclitaxel-acute pain syndrome might be a positive step in the development of effective prevention and/or treatment strategies. With the hypothesis that the paclitaxel-acute pain syndrome occurs as a result of nerve injury, an observational study to clarify the clinical characteristics of this syndrome was initiated. Methods: Oncology patients who were treated with at least one dose of paclitaxel and reported developing sub-acute pain were questioned using a detailed structured interview. Various aspects of the pain, including the time of onset, duration, location, severity, and exacerbating factors were evaluated. Data were tabulated descriptively. Results: Eighteen patients were interviewed. The onset of pain typically occurred 1–2 days after therapy and lasted for a median of 4–5 days. Pain was most commonly located in the back, hips, shoulders, thighs, legs and feet, with the most common descriptors used being ‘aching’ or ‘deep pain’. Commonly used adjectives to describe the pain were: ‘radiating’, ‘shooting’, ‘aching’, ‘stabbing’ and ‘pulsating’. Some patients described increased pain with weight bearing or walking. Fifteen of 18 patients specifically denied localization of pain to either joints or muscles. Conclusions: The nature of the pain, i.e. , generalized, deep aching pain, the notation of increased sensitivity with weight bearing (mechanical hyperalgesia) and the lack of localization to joints or muscles, support the hypothesis that the paclitaxel-acute pain syndrome results from a hyperalgesic dysfunction of nociceptive receptors, their fibers, or the spinothalamic system. These clinical conclusions are supported by the recent findings that markers of cellular injury can be identified in peripheral nerve tissues shortly following paclitaxel administration in an animal model (Peters CM, et al., Exp Neurol. 2007 Jan;203(1):42- 54). No significant financial relationships to disclose.
Long-Term Update from the Open-Label Extension of the NEURO-TTR Study in Patients with Hereditary Transthyretin Amyloidosis
Brannagan, Thomas H., Wang, Annabel K., Coelho, Teresa , Polydefkis, Michael , Dyck, P. James B. , Merlini, Giampaolo , Hughes, Steven G. , Kwoh, Jesse, Jung, Shiangtung W., Guthrie, Spencer , Pollock, Michael, Benson, Merrill D., Merlini, Giampaolo , Waddington‐Cruz, Márcia , Planté‐Bordeneuve, Violaine , Berk, John L. , Barroso, Fábio , Conceição, Isabel , Gertz, Morie A.

Blood | October 14, 2019 | Volume: 132 | Issue: Supplement 1 | Pages: 498-498

10.1182/blood-2018-99-116995 Get It

Abstract Background: Hereditary transthyretin amyloidosis (hATTR) is a rare, progressive, and fatal disease caused by the buildup of transthyretin-derived amyloid protein in major organs, predominantly affecting the peripheral nerves and heart. Inotersen, a second-generation antisense oligonucleotide targeting TTR mRNA, has shown efficacy and safety in patients with hATTR in a randomized, double-blind, placebo-controlled, phase 3 study, NEURO-TTR (ClinicalTrials.gov, NCT01737398; Benson NEJM 2018). Patients with hATTR amyloidosis who completed the NEURO-TTR study were eligible to receive inotersen for up to 5 years in a phase 3 open-label extension study (ClinicalTrials.gov, NCT02175004). Methods: In NEURO-TTR, patients were randomized 2:1 to receive inotersen (300-mg weekly subcutaneous doses) or placebo. In the open-label extension, patients continued inotersen (inotersen-inotersen) or switched from placebo to inotersen (placebo-inotersen). Evaluations included modified Neuropathy Impairment Score +7 neurophysiologic tests composite score (mNIS+7; higher scores indicate worse neuropathy), Norfolk Quality of Life-Diabetic Neuropathy questionnaire total score (Norfolk QoL-DN; higher scores indicate worse QoL), and adverse events (AEs). Cardiomyopathy (CM) was defined by a diagnosis of hATTR-CM at trial entry or by an interventricular wall thickness of 13 mm or more on transthoracic echocardiography at baseline, as ascertained by a central reader, or no known history of persistent hypertension (systolic blood pressure, ≥150 mm Hg) within 12 months before screening. Results : In the placebo-controlled, double-blind, phase 3 NEURO-TTR study, 112/172 patients were randomized and received inotersen. At baseline, patients were predominantly white (91.9%) males (68.6%) with a mean age of 59.2 years. A total of 67.4% had stage I (ambulatory) and 32.6% had stage II (ambulatory with assistance) disease. Inotersen-treated patients who had stage II disease had a longer duration of disease from diagnosis (40.9 vs 24.8 months, respectively) and from onset (72.6 vs 63.2 months, respectively) of hATTR polyneuropathy symptoms compared with placebo-treated patients who had stage II disease, indicating more advanced disease. A higher proportion of inotersen-treated patients had CM at baseline (67% vs 55%, respectively), and more severe CM, measured by higher NT-proBNP levels and longer duration of disease from hATTR-CM symptom onset, compared with placebo-treated patients. In the phase 3 open-label extension study as of Sept 15, 2017, 134 of 135 patients enrolled received ≥1 dose of inotersen. The mean age was 60.4 years and most patients were male (69.4%). Extended dosing with inotersen up to 27 months continued to improve mNIS+7 and Norfolk QoL-DN in the open-label extension compared to placebo-treated patients at week 66 in the double-blind NEURO-TTR study; mean changes from open-label extension baseline to open-label extension week 52 in the inotersen-inotersen group were 5.1 points for mNIS+7 (vs 25.5 for placebo-treated patients in the double-blind NEURO-TTR study) and 3.9 points for Norfolk QoL-DN (vs 10.7 for placebo-treated patients in the double-blind NEURO-TTR study). Initiation of inotersen in placebo-treated patients (placebo-inotersen) resulted in improvement in mNIS+7 and Norfolk QoL-DN by week 26. Few patients discontinued treatment because of AEs (inotersen-inotersen, 9%; placebo-inotersen, 4%). The rate of treatment-related serious AEs was low in both treatment groups (2% each). There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of exposure. We will present 2-year follow-up results from the open-label extension study. Conclusions: Results of the open-label extension show continued benefit, measured by mNIS+7 and Norfolk QoL-DN, and confirmed that earlier initiation of treatment is important for optimal clinical outcomes. No new safety concerns were identified. Results from the longer-term follow-up for the open-label extension will further elucidate how inotersen may benefit patients with hATTR amyloidosis. Disclosures Brannagan: Alnylam: Honoraria, Other: Investigator, Speakers Bureau; Ionis: Other: Investigator. Wang:Ionis: Other: Investigator, Speakers Bureau. Coelho:Prothena: Consultancy, Honoraria; Ionis: Consultancy, Other: Investigator; Alnylam: Consultancy, Honoraria, Other: Investigator; Pfizer: Consultancy, Honoraria, Other: Investigator. Waddington Cruz:Ionis: Honoraria; Genzyme/Sanofi: Honoraria; Pfizer: Honoraria. Polydefkis:Pfizer: Honoraria; Alnylam: Honoraria. Dyck:Ionis: Consultancy; Alnylam: Consultancy. Plante-Bordeneuve:Alnylam: Consultancy; Pfizer: Consultancy, Other: reimbursement for travel and meeting; Ionis: Other: reimbursement for travel and meeting. Berk:Ionis: Honoraria, Other: Investigator; Alnylam: Honoraria, Other: Investigator; Pfizer: Other: Investigator. Barroso:Pfizer: Consultancy, Honoraria, Other: Thaos registry, Speakers Bureau; Alnylam: Honoraria, Other: Investigator. Conceição:Alnylam: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Sanofi: Honoraria, Speakers Bureau. Hughes:Ionis: Employment. Kwoh:Ionis: Employment. Jung:Ionis: Employment. Guthrie:Akcea: Employment. Pollock:Akcea: Employment. Benson:Ionis: Other: Investigator, Research Funding. Gertz:janssen: Consultancy; Teva: Consultancy; spectrum: Consultancy, Honoraria; Alnylam: Honoraria; Ionis: Honoraria; Amgen: Consultancy; annexon: Consultancy; Prothena: Honoraria; Research to Practice: Consultancy; Apellis: Consultancy; celgene: Consultancy; Abbvie: Consultancy; Medscape: Consultancy; Physicians Education Resource: Consultancy.
Transthyretin amyloidosis: Putting myopathy on the map
Pinto, Marcus Vinícius , Milone, Margherita , Mauermann, Michelle L. , Dyck, P. James B. , Alhammad, Reem , Grogan, Martha , Liewluck, Teerin , Pinto, Marcus V , Liewluck, T , Mauermann, Michelle L , McPhail, Ellen Darcy

Muscle & Nerve | October 6, 2019 | Volume: 61 | Issue: 1 | Pages: 95-100

10.1002/mus.26723 | PMID 31587306 Get It

Abstract Introduction Although peripheral neuropathy and cardiomyopathy are well‐recognized manifestations of transthyretin (ATTR) amyloidosis, myopathy has been rarely reported. Methods In this study we reviewed our muscle biopsy database (January 1998 to June 2018) to identify patients with ATTR amyloid myopathy confirmed by molecular or proteomic analysis. Clinical and laboratory findings were reviewed. Results We identified eight ATTR amyloid myopathy patients (5 hereditary ATTR [ATTRv] and 3 wild‐type ATTR [ATTRwt]). Myopathy was the initial manifestation in all ATTRwt patients and followed peripheral neuropathy (4 patients) or cardiomyopathy (1 patient) in ATTRv patients. One ATTRv patient developed myopathy after liver transplant. Peripheral neuropathy and cardiac amyloidosis occurred in seven and six patients, respectively. Muscle biopsy showed interstitial amyloid deposition in all patients, rare necrotic/regenerating fibers in six, and vacuoles in four. Discussion Myopathy can be the initial manifestation of ATTRwt amyloidosis and can precede the peripheral neuropathy or occur after liver transplant in ATTRv amyloidosis.
Dominant collagen XII mutations cause a distal myopathy
Mohassel, Payam , Liewluck, Teerin , Hu, Ying , Ezzo, Daniel, Ogata, Tracy, Saade, Dimah , Neuhaus, Sarah , Bolduc, Véronique , Zou, Yaqun , Donkervoort, Sandra , Medne, Līvija , Sumner, Charlotte J. , Dyck, P. James B. , Wierenga, Klaas J. , Tennekoon, Gihan, Chen, Jiani , Winder, Thomas , Staff, Nathan P. , Foley, A. Reghan , Koch, Manuel , Bönnemann, Carsten G. , Liewluck, T , Staff, Nathan P , Finkel, Richard S. , Winder, Thomas L., Donkervoort, Sandra

Annals of Clinical and Translational Neurology | September 11, 2019 | Volume: 6 | Issue: 10 | Pages: 1980-1988

10.1002/acn3.50882 | PMID 31509352 Get It

AbstractObjectiveTo characterize the natural history and clinical features of myopathies caused by mono‐allelic, dominantly acting pathogenic variants in COL12A1.MethodsPatients with dominant COL12A1‐related myopathies were characterized by history and clinical examination, muscle imaging, and genetic analysis. Pathogenicity of the variants was assessed by immunostaining patient‐derived dermal fibroblast cultures for collagen XII.ResultsFour independent families with childhood‐onset weakness due to novel, dominantly acting pathogenic variants in COL12A1 were identified. Adult patients exhibited distal‐predominant weakness. Three families carried dominantly acting glycine missense variants, and one family had a heterozygous, intragenic, in‐frame deletion of exon 52 of COL12A1. All pathogenic variants resulted in increased intracellular retention of collagen XII in patient‐derived fibroblasts as well as loss of extracellular, fibrillar collagen XII deposition. Since haploinsufficiency for COL12A1 is largely clinically asymptomatic, we designed and evaluated small interfering RNAs (siRNAs) that specifically target the mutant allele containing the exon 52 deletion. Immunostaining of the patient fibroblasts treated with the siRNA showed a near complete correction of collagen XII staining patterns.InterpretationThis study characterizes a distal myopathy phenotype in adults with dominant COL12A1 pathogenic variants, further defining the phenotypic spectrum and natural history of COL12A1‐related myopathies. This work also provides proof of concept of a precision medicine treatment approach by proposing and validating allele‐specific knockdown using siRNAs specifically designed to target a patient’s dominant COL12A1 disease allele.
Putative mechanisms for spread and transformation of cutaneous T‐cell lymphoma to neurolymphomatosis
Puffer, Ross C. , Dyck, P. James B. , Paul, Pritikanta , Amrami, Kimberly K. , Spinner, Robert J. , Paul, Pritikanta , Broski, Stephen M.

Muscle & Nerve | August 15, 2019 | Volume: 60 | Issue: 5 | Pages: No page available

10.1002/mus.26670 | PMID 31415100 Get It

Update on classification, epidemiology, clinical phenotype and imaging of the nonsystemic vasculitic neuropathies
Collins, Michael P. , Dyck, P. James B. , Hadden, Robert D. M.

Current Opinion in Neurology | July 15, 2019 | Volume: 32 | Issue: 5 | Pages: 684-695

10.1097/wco.0000000000000727 | PMID 31313704 Get It

Purpose of review Single-organ vasculitis of the peripheral nervous system (PNS) is often designated nonsystemic vasculitic neuropathy (NSVN). Several variants or subtypes have been distinguished, including migratory sensory neuropathy, postsurgical inflammatory neuropathy, diabetic radiculoplexus neuropathies, skin-nerve vasculitides, and, arguably, neuralgic amyotrophy. NSVN often presents as nondiabetic lumbosacral radiculoplexus neuropathy (LRPN). This review updates classification, clinical features, epidemiology, and imaging of these disorders. Recent findings A recent study showed the annual incidence of LRPN in Olmstead County, Minnesota to be 4.16/100 000:2.79/100 000 diabetic and 1.27/100 000 nondiabetic. This study was the first to determine the incidence or prevalence of any vasculitic neuropathy. In NSVN, ultrasonography shows multifocal enlargement of proximal and distal nerves. In neuralgic amyotrophy, MRI and ultrasound reveal multifocal enlargements and focal constrictions in nerves derived from the brachial plexus. Histopathology of these chronic lesions shows inflammation and rare vasculitis. Diffusion tensor imaging of tibial nerves in NSVN revealed decreased fractional anisotropy in one study. Summary Single-organ PNS vasculitides are the most common inflammatory neuropathies. Neuralgic amyotrophy might result from PNS vasculitis, but further study is necessary. The usefulness of focal nerve enlargements or constrictions in understanding pathological mechanisms, directing biopsies, and monitoring disease activity in NSVN should be further investigated.